1. Field of the Invention
The invention relates to portable computing, and more specifically to the sharing of data between handheld computer systems and desktop and/or portable computer systems.
2. Description of the Related Art
The rapid acceptance of computer technology by corporations as well as consumers has led to the widespread use of computers. Further abetting this process is the continual reduction in size and cost of personal computers. Originally, personal computers were large items best suited for floor standing or desktop use. Eventually, they became smaller so that desktop use became the standard. Improvements in processor, memory and data storage capabilities have resulted in light weight, powerful mobile computers such as portables, luggables, laptops, notebooks, palm top and personal digital assistants. These computers can provide sufficient processing capability for audio visual applications, such as computer aided design, three dimensional animation, and multimedia presentation, even when used at remote locations.
As the use of personal computers increased, so did the desire to use computers remotely to support and increase the efficiency of mobile users. However, in most cases, notebook computers were effectively just small versions of full-function desktop computers and so were relatively expensive. Further, they were also relatively heavy and conspicuous to use. The unfavorable attributes of size, expense, and operating period limited the usefulness of notebook computers in certain applications, namely those that required on-the-spot data proessing with inconspicuous and transparent computing capability.
One variant of small factor notebook computers is referred to as notepad or touchpad computers. These computers were essentially notebook computers with the keyboard removed and a digitizer applied to the display so that a pen or other suitable pointing devices could be used as an input device. The use of a pen freed up one aspect of the computer size requirement, namely the requirement for keyboards of certain given dimensions. However, because the handwriting recognizers in these palmtop or handheld computers were not always 100% accurate, these pen-based notepad computers had to be geared to specific applications which utilized special hardware or operating programs such as inventory control and others where simple check-offs could be utilized or somewhat constrained input patterns could be entered. These limitations hampered the usage of the palmtops to only specific applications. Further, most of the original notepad units were based directly on a notebook computer form factor and as such came in sizes of approximately 81/2.times.11 inches and 1 inch thick, and weighed 5 to 6 pounds. Thus, these notepad units were quite heavy and inconvenient, in that they could not be carried for extended periods. Further, the performance of these portable devices was dramatically reduced to achieve the necessary minimum power consumption.
Recently, a new class of portable computers called palmtop or handheld units has emerged. Some of these units offer very limited functionality and are typically restricted to being personal organizers. These watered-down computers are not compatible with programs on larger desktop and notebook computers, but rely on proprietary operating systems and programs to ensure small memory footprint and quick response time, even on low-power microprocessors. These restrictions limited the usefulness of the personal organizers, as they operate stand alone and cannot readily share data with other computers. Additionally, some units were also developed which did offer common functionality with the desktop computers, but were generally keyboard based and the use of tiny keyboards made them relatively unusable to a large segment of the population. Exemplary palmtop or handheld devices with miniature keyboards include the HP-200LX, available from Hewlett-Packard Corporation. Furthermore, palmtop or handheld devices with pen interfaces have appeared. These devices include the Newton and the Pilot available from Apple Computer Corporation and U.S. Robotics Corporation, respectively. Further, palmtop computers with both a keyboard and a pen have also appeared, including the Zaurus ZR-5700/5800, available from Sharp Corporation.
To balance between the ease of reading and editing files on a desktop computer and the convenience of collecting information and operating the palmtop or handheld when the user travelled, the user typically purchased both the desktop computer and the palmtop computer. The two platforms were linked via one or more communication paths, including paths through a modem, a parallel port, a serial port, or a cradle assembly connected to the host computer. Further, various wireless communication techniques, such as radio or infrared communication may be used. In the event that a cradle was used, when the handheld computer was in the cradle and actively connected to the host computer, the handheld computer typically entered a mode to update data in the host computer and itself.
A major problem exists in the current methods of synchronizing data between the desktop computer and the palmtop or handheld computer. For instance, certain data such as calendar information, appointment information, and notes, among others, would generally be kept on a desktop computer which may be networked so that other workstations may remotely update the calendar information, appointment information, and notes. The same information was also kept on the palmtop or handheld computer for the user to review and update when mobile. However, if the user was traveling and information was entered on the desktop computer or on a remote station on a network server machine while the user was not at his or her office, or if the user entered information on the local version of the data in the palmtop or handheld computer, the information contained in the desktop computer and the palmtop or handheld computer would become non-coherent, leading to undesirable problems such as meeting conflicts and miscommunications.
The prior resolutions of the data synchronization problem were generally very time consuming and tedious and therefore reduced the effectiveness of the palmtop/desktop combination. One solution was to limit the accessibility of files such that only files physically residing with the user were the master. However, this solution dictated that no changes could be made to the other system without the danger of losing those changes. Thus, while the palmtop/desktop combination of computers existed, the use of the combination was not popular due to the requirement that the user had to manually synchronize the data on both platforms. Therefore, the problem of synchronization limited the potential of the palmtop or handheld computer market.
One problem encountered by the current generation of handheld devices and their add-on connectivity solutions is that the connectivity solutions rely on batch mode rather than real-time oriented approaches to data coherency. Because the desktop and the handheld device typically became disconnected and incommunicado when the user goes mobile, the data synchronization problem becomes intractable. During the mobile period, the creation, the deletion and the modification of data causes incoherency that often results in conflicts reconcilable only through manual intervention by the user. These conflicts would arise because the desktop and handheld device were unable to communicate changes in their data until they were reconnected using a serial, parallel or modem connection.
Because data coherency is a real time problem, a real time solution that avoids data conflicts by shortening the time between synchronization events is needed. Therefore, it is desirable to have a small handheld computer system capable of operating certain personal information type software, such as calendars, telephone directories and to do lists, as well as simplified versions of desktop application software, and sharing data with a desktop computer, with all the data utilized by all of the programs being dynamically synchronized to alleviate the data coherency problem.